Automatic telephone system



' June 5, 1928.

J. E. OSTLINE AUTOMATI C TELEPHONE SYSTEM 3 Sheets-Sh et 1 Filed Feb. 2,

Inuen.ur Jnhn E- UETZmE June 5, 1928.

J. E. OSTLINE AUTOMATIC TELEPHONE SYSTEM 2 t V m WQQ S s t e e h s 3 5 2 9 l 11 e F d e l i June 5. 1928. v 1,672,336 J. E. OSTLINE AUTOMATIC TELEPHONE SYSTEM Filed Feb. 2, 1925 3 Sheets-Sheet 3 Jcfim E. [73712215.

W HIT y:

-Patented June 5, 1928.

UNITED STATES,"

WARE.

P TENT" oF'rlcE.

JOHN, E. OSTLINE, OF LIVERPOOL, ENGLAND, ASSIGNOR, BY MEs'nE ASSIGNMENTS, r0 AUTpMA'rIo ELECTRIC 1110., or cnrcaeo, ILLINOIS, A conPonA'rIoN or DELA- AUTOMATIC TELEPHONE SYSTEM.

) Application fil ed February 2, 1925. Serial No. 6,240.

The present invention relates toautomatic telephone systems in general, but s concerned more particularly with automatic telephone systems in which arrangements are provided for n'iaking'so-called two-number toll calls,- and the broad general obgectis theprovision of an effective arrangement whereby the toll operator may readily and accurately check the number of the calling subscriber as given to herverbally when the call reaches her position.

According to a special. feature of thein? vention, operator-controlled. arrangements are provided for placing on the private 1101' mal conductor of the line bearing thenumber given the operator a high frequency potential, which, if the number given is the correct one, results in a flow of high fre quency current over such private normal conductor and forward over the release trunk conductor ofthe established connection to the operators position where suitable arrangen'lents are provided for detecting this' flow of current and for notifying the operator of its presence. v a I According to another-feature of the 1nvention, the operator is notified of the cor-' rectnes's or the incorrectness of the number by the lighting of one or the other of two lamps after she has dialled the number given to her by the calling subscriber. If the number is correct the White lamp lights. If the number is incorrect, the red lamp lights. I

According to another feature of the in vention, the equipment. provided at the operators position for checking the correctness of a calling subscribers number is common to the several cord circuits at her position. According to another feature of the in-.

vention, a sequence switch is provided at the operators position which operates under the control of the calling device and advances one step for each digit dialled. This switch automatically brings in the number-verified lamp or the number-incorrect lamp at the proper time. I

The other objects and features of the invention are mainly subsidiary to the foregoing and are concerned principally with the circuit details involved in carrying out theinvention. These objects and features, together with the foregoing, will be readily appreciated upon a further perusal of the specification.

Referring now to the drawings comprising Figs. 1-3, inclusive, they show by means of the usual circuit diagrams a sufficient amount of equipment in a telephone system embodying the features of the invention to enable the; invention to be'understood and its utility to be appreciated.

The system shownas'assumed to comprise a multi-otfice automatic telephone system comprising less than ten automatic oflic'es. Tt'is assumed further that connections'to outlying suburban exchanges are completed by the toll operator according to the twonumber or express service plan, i. e., a subscriber, desiringsuch service, dials the digit necessary to extend a connection to the express operators position, and he gives the number to the express operator when she responds. The express operator then completes the connection while the calling subscriber waits, as is the usual practice in connection With such service as contrasted with the practice used in handling regular long distance calls, whereinthe calling subscriber replaces his receiver and is recalled by the long distance operator when the connection is ready.

Regarding'the-layout of the equipment and the trunking arrangement, the line of substantion A, Fig. 1-,ter'minates at the ex change in the line sWitchLS and also in the banks of connector switches (not shown).

The line switch LS ha access to the first selectors and to othersimilar first selectors.

The first selector S has access on one level to a number of repeaters, one of which is the repeater R, Fig. 2.

The repeater R- has associated.therewith, a trunk line T, Whichextends 110111 the automatic otlice to the office in which the express operator is located and terminates in the jack J at the operators position.

The operator is provided witha number of The conductors 1-51 and 152 associated with the repeater R,Fig. 2, terminate 'in is one, and she has at her positiona number toll lines, such as the toll line TL, over til the banks of finders, such as the finder F, and, when the start wire 180 associated with the repeater R and the other similar repeaters is grounded, a finder,1such as F, finds the repeater R.

The finder F has associated therewith a verification selector VS and this selector has access on one level to a. second verification selector VS which inturn has access on one level to a verification connector V0. The connector VC has acccssto the private normal conductors of 100 ,calling lines. In short, the local trunking system within the automatic oiiice is reproduced in miniature by verification selectors and connectors, such as the selectors VS and VS and the verification connector VC.

The line switch LS is mechanically oi the well known rotary type in which the wipers have no normal position and move in a for ward direction only. The wipers are advanced upon the back stroke of the associated stepping magnet rather than upon the forward stroke. From a purely mechanical standpoint, the sequence switch S is of the same rotary-type oi. switch as the line switch LS.

The selector S and the verification selectors and connectors are of the well known vertical and rotary type of switch and their bank contacts are arranged in horizontal rows or levels.

The system having been described generally, a detailed description of the operation of the apparatus shown will now be given. For this purpose, it will be assumed that the subscriber at substation A desires to make an express call to -a nearby suburban exchange. That being the case, the subscriber at substation A removes his receiver, whereupon line relay 3 energizes over the con- 'duetors of the calling line and closes at armature T a circuit through switching relay 2 and stepping same time placing ground on the associated private normal conductor so to guard the calling line against intrusion. As a further result of its energization, line relay 3 connects test wiper 11 at armature 8 to the junction oi? relay 2 and magnet 9.

In case the trunk upon which the wipers ot the line switch LS are standing is idle, this latter operation has no particular utility at the present time-and switching relay 2 energizes, seizing the trunk. Assuming on the other hand that the aforementioned trunk is busy, the bank contact upon which test wiper 11 is standing is grounded, and switching relay 2. being short circuited, does not energize. Under this condition, a circuit is closed for the self-interrupting stepping magnet 9 and the wipers 1()-12 are advanced step by'step in search of an idle trunk;

When an idle trunk is reached, which magnet 9 in series, at the trunk, it will be assumed, is the one com prising conductors l3-15, the self-interrupting action of the stepping magnet 9 ceases on account of the fact that no ground is at that time encountered by the test wiper 11, and switching relay 2, being no longer short circuitcd, energizes in series with stepping magnet 9. Stepping magnet 9 dOes not pull up at this timeo'n account of the relatively high resistance of switching relay 2. Upon pulling up, relay 2 disconnects at armatures 4 and 6 the conductors of the calling line from line relay and ground and extends them by way of wipers lOand 12, conductors 13 and 15, and armatures 37 and 40. to the windings of line relay 21 of the selector S, and at armature 5 disconnects test wiper 11 from the junction of its own wind ing and connects it to the grounded private normal conductor, thereby placing ground on release trunk conductor 14. This makes the seized trunk busy immediately. 1

In the selector S, line relay 21 energizes responsive to the above operation of switching relay 2 of the line switch LS and closes at armature 31 a circuit for release relay, 22, which thereupon energizes; opens a point in the circuit of release magnet 26 at armature and prepares a circuit for vertical magnet 47; and at armature 32 places ground on release trunk conductor 14, thereby establishing the'usual holding circuit for switching relay 2 oi": the line switch LS before the slow acting line relay 3 has had time to fall back.

hen the calling subscriber dials the digit gizes, line relay 21 closes at armature 31 a circuit through armature 83 and its working contact and series relay 23 for vertical magnet 47. By the operation of vertical magnet 47, the wipers 41-43 are raised step by step and come to rest opposite the desired level of bank contacts. Relay 28 is energized in series with vertical magnet 47, and,-being slow acting, maintains its armature attracted throughout the vertical movement. Upon the closure oi'ofi normal contacts 30, responsive to the first vertical movement of the shaft, stepping relay 24 energizes from the grounded release trunk con ductor 14 through armature 34 and its working contact, oii normal contacts 30, and in terrupter contacts 29. Upon energizing, relay 24 closes at armature 35 a locking circuit for itself and at armature 36 .prepares a. circuit for rotary magnet 28.

At the end of the vertical movement, slow acting relay 23 falls back and at armature- 34completes a circuit for rotary magnet 28.

the first set of bank contacts in the selected level, and,near the end of its stroke, opens at interrupter contacts 29 the circuit of step ping relay 24. lVhen this occurs, relay 24 deenergizes and opens the circuit of rotary magnet 28 at armature 36, whereupon r0 tary magnet 28 deenergizes also and closes its interrupter contacts 29 again.

The further operation depends upon whether the first trunk is busy or idle. If it is idle, switching relay 25 energizes right away, seizing the trunk. Assuming on the other hand that the trunk is busy, test wiper 42 engages a grounded test contact and switching relay 25 is short circuited. In this case, stepping relay 24 energizes again through the test wiper and closes again the circuit of rotary magnet 28 which thereupon energizes and advances the Wipers'another step. This alternate operation of stepping relay 24 and rotary magnet 28 continues as described until an idle trunk is reached, which trunk, it will be assumed, is the one comprising conductors 44-46. When this idle trunk is reached, switching relay 25,

being no longer short circuited, energizes in series with stepping relay 24. Stepping relay 24 does not energize at this time on account oi 'the high resistance of switching relay 25. Upon energizing, relay 25 opens the test circuit and prepares the holding circuit at armature 38; disconnects ground from armature 31 of line relay 21 at armature 39, thereby opening the circuit of the slow acting release relay 22; and at armatures 37 and 40 disconnects the line conductors 13 and 15 from the windings of line relay 21 and extends them by way of wipers 41 and 43, the bank contacts upon which these'wipers are standing, conductors 44 and 46, and the upper and lower windings of line relay 101 or the repeater R, to battery and ground, respectively. Line relay 101 now energizes over the calling line and closes at armature 111 a circuit for relay 102. Belay 102 now energizes and places ground 011 release trunk conductor 45'at armature 113 through the low wound impedance 126, thereby establishing the usual holding circuit for the selector S and the line switch LS before the slow acting release relay 22 of the selector S has had time to deenergize. I

As a further result of its energization, line relay 101 of the repeater R connects at armatures 110 and 112 the back bridge relay 105 of the repeater R to conductors 128 and 129 or" the trunk line T through the normally closed contacts controlled by armatures 110 and 117 of the reversing relay 104. hen this occurs, the high wound line relay 201 of the trunk circuit TC, Fig. 3, energizes over conductors 128 and 129 in series with back bridge relay 105 of the repeater R and closes at armature 205 a circuit for the line lamp 206. Back bridge relay 105 of the repeater on the other cord circuits. many a bridge across the conductors 221 B does not pull up at this time on account of the relatively high resistance of line relay 201 of the trunk circuit T C.

The operator, upon notingthe lighted condition of the lamp 206, inserts the answering plug of a cord circuit, for example,

the plug P ofthe cord circuit CC, into the jack J. WVhen this occurs, cut-01f relay 202 of the trunk circuitTC energizes in series with sleeve relay 207 of the .cord circuit CC and cuts off the line relay 201 at armatures 203 and 204. The talking strands of the cord circuit CC are now connected to conductors 128 and 129 through the plug P and the jack J and the lront bridge relay 208 now energizes over conductors 128 and 12,9

and in series with the back bridge relay of I the calling subscriber, finding out the de.-'

sired number and also the number of the calling line. i I

From this point on, several courses are open to the operator. For example, she may proceed to get in touch-with the operator at the distant end'of the toll line TL and order up the number, and check the calling subscribefsnumber while the distant operator is completing the operation; she may first verify the calling subscribers number; or, as a third alternative, she may divide her time between the two processes, all as she sees fit, or according to the instructions giv en by someone in authority. In the present case,.however, it will be assumed that the operator first proceeds to verify the number of the calling subscriber. In order to do this, the operator throws the key K into its alternate position, thereby disconnecting the talkingstrands of the plug P from the bridge including relay 208 and permitting relay 208 to fall back and light the lamp 211. The key K also grounds conductor 222. thereby closing a circuit through the right hand contacts of the key BK for relay 224 which pulls up and opens up the restoring circuit of the sequence switch S. As a still further result of the operation of the key K, the talking strands of the plug P are connected to conductors 221 and 223 which are multipled to the corresponding contacts There is norand 223 including the left hand contacts of the release key BK, sending contacts of the calling device CD, and Wiper 235 and its normal contact of the sequence switch S.

In the repeater R, back bridge relay 105 now energizes over the trunk line '1 and through the bridge in the operators equipment, as above traced; disconnects the test conductor 151 from ground through armature 122 at armature 120 and connects it instead to relay 106; and at armature 119 it places ground on the start conductor 130 through armature 121 and its resting contact. Assuming that the finder F is at this time idle, the placing of ground upon start conductor 130 results in the closure of a circuit through armature 148 and its resting contact for start relay 141. Accordingly, relay 141 energizes and closes at arn'iature 145 a circuit for switching relay 142 and stepping magnet 143 in series, and at armature 144-connccts test wiper 149 to the junction of relay 142 and magnet 143. Assuming that the wipers 149 and 150 are standing on the bank contacts associated with some other repeater, as shown in the drawings, test wiper 149 is in engagement with a grounded bank contact and relay 142 is short circuited and does not energize.

\Vhen the wipers of the finder l? arrive on the contacts associated with the repeater R, the operation of the stepping magnet 143 automatically ceases on account of the absence of the ground potential on conductor 151 and on the associated test contact. Also,

switching relay 142, being no longer short circuited, now energizes in series with magnet 143. At armature 147, relay 142 opens the test circuit and places ground on test wiper 149; connects up wiper 150 at armature 155; and at armature 148 disconnects the start conductor 130 from start relay 141 and extends it to armature 146 of the energized start relay 141. The s art conductor is not extended on to the next finder immediately on account of the fact that relay 141 is slow acting and does not fall back imn'iediately.

1n the re iieater R, relay .106 energizes through arn'iaturc 120 and its working contact responsive to the placing of ground upon conductor 151 by the tinder F, as above pointed out, and, at ari'nature 121, disconnects ground from the start conductor 130 and connects ground to conductor 152. Relay 106 also removes ground from the resting contact of relay 105 at armature 122, and at armature 123 locks itselfto conductor 151 independent of armature 120 and its rorking contact. At armature 124 relay 106 closes a circuit for cut-off. relay 108 which opens the talking circuit at armatures 114 and 115 so as to prevent the calling subscriber from being annoyed by the dialling operation which is to take place sub-' sequently. A circuit is closed through relay 104 and the resistance 109 in parallel with relay 103, but relay 104 does not pull up at this time because it is short circuited through armature 118 and its resting con act and the contacts of the high frequency. relay 107.

As a result of conductor 152 being grounded at arn'iature 121 of relay 106, as above pointed out, line relay 161 of the ver-- iii-cation selector VS energizes through the working contact and arn'iature 1190f back bridge relay 105 of the repeater R, armature 1.21 and its working contact, conductor 152, wiper 150 of the finder F, working con tact and armature 155, and the lower armature and resting contact of the switching relay of the verification selector VS. lit may be pointed out here that the selector VS is similar to the selector S, Fig. 1, with the exception that only one line conductor is used because no talking circuit need be established through the verification selector. Accordingly. it is thought that no detailed explanation need be given of the verification selector. It will sufliee to say at this point that the associatedrelease relay pulls up in response to the energization of the line relay and places ground on release trunk conductor 153 thereby closing the usual holding circuit for switching relay 142 of the finder F and for relay 106 of the repeater R before the slow acting start relay 141 of the finder F has had time to deenergize. Yr

After the interval for which it is adjusted, relay 141 deenergizes and extends start conductor 130 to the next finder at armature 146. This delay in the extension of the start circuit is made in order to, insure that the ground potential applied tojthc start conductor 130 by the repeater R has been removed at armature 121 of relay 106 before such extension occurs. Otherwise, a momentary false operation of the finder might result. If this precaution were not necessary, thestart wire would simply be extended to the next finder independent of armature 146 and its resting contact.

The circuits are now in readiness for the operator to dial thenumber given to her by the calling subscriber. lVhenthe operator turns the callingdevicejn accordance with the first digit in the numberof the calling subscriber, the sending contacts of the calling device CD are opened a corresponding number of times. The back bridge relay 105 of the repeater It deenergizes each time the sending contacts are opened. and it opens the circuit of line relay 161 of the verification selectorVS at armature 119, whereupon line relay 161 deenergizes. The result of this is that the verification selector VS raises its wipers opposite the desired level of bankcontaets .and automatically rotates them in search of a verification second selector in the proper level of bank contacts. lVh'en the wipers 162 and 16.3 arrive upon the contacts of an idle second selector, for example, the contacts in which conductors 16'4- and 165 terinitiate, the switching relay of the' switch VS energizes with the result that connection is switched through to the selector VS" which is accordingly prepared for operation in the usual manner. 1

Vhen the operator calls the second digit, the selector VS raises its wipers opposite the desired level and selects an idlexverilication connector, for example, the verification connector VS, Fig. 1. When this o'ccurs, relay energizes over "conductorsl65 and 64 and closes at armature 74 a circuit for release relay 66, whereupon release relay 66 energizes and places ground upon release trunk conductor 63 at armature 77, thereby establishing the usual holding circuit for the two verification selectors, the finder F, and relay 106' of the repeater It. At armature 78, relay 66 of the connector VG opens a point in the circuit of release magnet 73 and prepares a circuit for vertical magnet 69. At armature 76, relay 66 places ground on conductor 82, thereby starting the high frequency interrupter HF I to operating. .At armature 75, relay 66 connects the output conductor 83 (from the secondary winding of the high frequency interrupter HFI) through the resting' contact and armature 80 of series relay 68' to" the wiper 81. I

When the operator dials the third digit in the number of the calling subscriber, line relay 65 of the connector VG deenergizes a corresponding number of times due to the repeating action'of the backbrldge relay of the repeater R, and, upon each deenerg1zation, closes at armature 74 a circuit for vertical magnet 69, the circuit at the time of its first closure being'as follows: From ground by way of armature 74 aud ts resting contact ,'arma ture 78 and its working contact, contact of off normal spring 7 2 and saidspring, series relay 67, and vertical magnet 69 to battery. By the operation of vertical magnet 69, the wiper '81 is raised step by step and comes to rest opposite the desired level of bank contacts; Relay 67 energizes in series with vertical magnet 69, and,being slow acting, maintains its armature attracted throughout the vertical movement. At armature79, relay 67 maintains its own circuit and that of vertical magnet 69intact after the off normal springs 72 and the as soci'ated springs have shifted, as they do upon the first vertical step. At the end of thevertical movement, relay 67 dee'nergizes and transfers the operating circuit from the vertical magnet to the rotary magnet. v l

hen the operator dials thenext and last digit the desired number, the impulses transmitted by relay 65 at armature 74 and its resting contact ass. through armature 78 and its working cont-act, normally open line terminates. Relay 68 is energized' in series with ma net and at' armature 80 maintains wiper 81 disconnected during the rotary movement so as not to interfere with contacts passed over during such movement. Upon the termination of the rotary movement, relay 68 falls back and connects up wiper 81: at armature 80 to the output conductor 83 of the high frequency in er,

rupter HFI, whereupon the high frequency current is applied to the private normal conductor of the called line and passes forward oter' the release trunk conductor of the established connection to release trunk'conductor 45 of the repeater B and thence to ground through the impedance 126 and throu h the parallel path which includes the high Irequency relay 107 and'the condenser 127. Thearmature' of relay 107 vibrates response to this high frequency current and sets theadjace'nt weighted spring into motion so as to causeinterrupt-ions in the short circuit around relay 104. Accordingly, relaylOt energizes and at armature 118 opens a further pointin its previously closed short circuit, so that it will now remain energized independent of control from relay 108. As a result of its energization, relay 10 1 reverses the conductors 128 and 129 as regards their connection withthe windings of back bridge relay 105 soas to give the proper signal to the operator.

' Returning now to the operators cir cuit, the operation of the sequence switch S will be taken up and explained in detail. It will benoted that there is' a pair of off normal contacts on the calling device CD, which, each time the dial is turned ofi normal,,close a circuit for stepping magnet 232 of the sequence switch S. Thisconstruction'ofth'e sequence switch S is.v such that the wipers are advanced upon the dee ner} gization of the associated stepping magnet 225 rather than upon the energization. Accordingly, each time magnet225 deenergizes uponthe return of the calling device CD to normal, the wipers 234i and2 35 are advanced one step That being the case, at the end of diallingthe fourth digit the operator, the wiper 235, advancesout of engagement withthe fourth contact and -in-, toengagement with the fifth contact. This removes theshunt' previously closed around the polarized relay 224 and; places a. shunt around the sending contacts of'the calling from around the polarizedrelay 229 at wiper 235, polarized relay 229 energizes in series with the back bridge relay of the repeater R and lights the red lamp 227. This occurs,

it maybe pointed out, immediately, follow ing the transmission of the lastinipulse in the fourth digit and occurs, therefore, before the above mentioned-encrgization of relay 104 of the repeater R. Accordingly, in every case, relay 229 energizes in thepi'oper direction to light the red lamp 227. How.- ever, in the present case, the operation of relay 229 is followed closely by the operation of the reversing relay 10 1 of the repeater R, hereinbefore described. Accordingly, relay 229 energizes in the opposite direction when the above mentioned reversing relay 104 operates, with the result that the red lamp 227 iseXt-inguished and the white lamp 228 is lighted, in order to notify the operator that the number of the calling subscriber has been correctly verified.

The foregoing is what happens when the number given by the calling subscriber as his own is the correct one. It will be at once appreciated that, in case the number given by the calling subscriber is not the correct one, the verification connector does not find the private normal conductor of the established connection and the high frequency relay 108 is not operated and, of course, battery is not reversed and the red lamp 227, Fig. 3, remains lighted, serving as a warning to the operator that the number has not been verified. In this latter case, she may take such steps as she deems necessary in order to cope with the situation.v

To continue with the description of the operation,when the operator notes that the red lamp has become extinguished and that the white lamp has become lit, she restores the key Kof the cord circuit CC, thereby disconnecting the talking strands of the plug P from the conductors 221 and 223 and connccting them again to the high wound relay 208. Relay 229 falls back and puts out the lamp 228, and relay 208 pulls up and puts out the lamp 211. y

The upper contacts of the key K remove ground from conductor 222 with the result that relay 224i deenergizes and at armature 225 places ground upon the restoring wiper 23 1, thereby closing a circuit through the associated bank and the local interrupter contacts 223 for the stepping magnet 232. hen this occurs, the wipers 234 and 235 are rapidly spun around to their normal position, whereupon the operation stops on account of the fact that the normal contact in the bank of wiper 234 is left deadv at armature 7 1.

falling back, back bridge relay 105 opens at armature 119 the circuit of line relay 65 of the verification connector VG, whereupon line relay 65 deenergizes and opens the circuit of release relay 66 and incidentally closes again the circuit of rotary magnet zation of rotary magnet 70 is accompanied by an energization of relay 68 which disconnects wiper 81 at armature 80. After the interval for which it is adjusted, relay 66 falls back; opens atarmature a further point in the circuit through which high fre- The incidental energiquency current supplied to the wiper 81; re

moves ground at one point-from start conductor 82 at armature 76; removes ground from release trunk conductor 63 at. armature 7! and atarmature 78 opens the rotary magnet circuit and closes the release magnet circuit. This results in the. immediate deenergization of rotary magnet 70, and in the deenergization somewhat later of relay 68. The closure of the circuit of release magnet 73 through off normal contacts 71 results in the energization of release magnet 73 with the result that the wiper 81 restored to its normal position, whereupon the v circuit of magnet 73 is opened at off normal contacts 71. Y x 1 Responsive to the above mentioned reinoval of the ground potential from conductor 63 by armature 77 of relay 56, the verification selectors VS and VS are released in the usual manner and relay 1&2 of the finder F falls back. a

Asa further result of the above mentioned removal of the ground potential from the release trunk conductor 63 of the verification connector VG, the circuit of the relay 106 of the repeater'R,Fig. 2, is opened. This relay is made slightly slow acting so as to enable the connection to be released before it falls back and replaces ground on conductor 151 at armature 122, the back bridge relay 105 being now deenergized, as above pointed out. As a further result of the deenergization of relay 100, it opcnsthe circuit of relays 103 and 10-1 at armature 124. Relay 104; deenergizcs right away and reverses the Cllll'el'ltl'lDW in conductors 12S and 129 of the trunk line T back to normal, and the slow acting relay 103fallsback after the. reversal is completed and again closes the talking conductors at armatures 11 1 and 115.

The operator may now insert her plug P of the cord circuit CC, Fig. 3, into the jack of an idle trunk line, such, for example, as

a the jack Jof'the trunk line TL. lVhen this The application of battery and ground to the tip and ringconductors of the toll line TL through the supervisory relay 209 of the cord circuit CG results in the energization of the usual high resistance line relay (not shown) on the distant end otthe toll line TL at the suburban B operators position. The B operator now responds and completes the connection in the usual manner. lVhen the called man answers, the major portion of the winding of the high resistance line relay on the distant end of the toll line TL is short circuited in the usual manner, whereupon the supervisory relay 209 energizes and opens the circuit of theassociated supervisory lamp, thereby giving supervision to the operator.

The two subscribers may now converse with each other in the'usual manner.

V hcn the conversation is terminated, the two subscribers will replace their receivers.

lVhen the receiver is replaced at the called substation, the resulting circuit operations are such that the resistance across the toll trunk line TL at the distant end is again increased and relay 209 falls'back and lights the associated supervisory lamp;

lVhenthe receiver is replaced at the calling substation A, line relay 101 of the repeater B, Fig, 2, falls back and opens atarmatures 110 and 112 the bridge across the trunk line T, whereupon the supervisory relay 208 in the cord circuit CC, Fig. 3, falls back and lights the associated supervisory lamp 211. The operator, upon noting the lighted condition of both supervisory lamps, pulls down the connection.

As a further result of the deenergization of the line relay 101 of the repeater R, it opens at armature 111 the circuit of release relay 102, with the result that release relay 102 deenergizes after an interval and removes ground from release trunk conductor at armature 113, whereupon switching relay'25 of the selector S and switching relay 2 of the line switch LS dcenergize. Responsive to the deenergization of switching relay 25 of the selector S, a circuit is closed at'armature 39 through armatures gland 33 and ofi normal contacts 27 for release magnet 26,

whereupon release magnet 26 energizes and the wipers 41-t3 are restored to normal position in the usual manner. The circuit 01"? release magnet 26 is opened at oil normal contacts 27. The entire connection is now released. r

Referring now particularly to F ig; 3, it will be noted that the operator is provided with a release key RK, which (along with the calling device and the associated equipment) is common to all the cord, circuits, such as CC. This release key is provided so that the operator may quickly release any partly set up verification connections through selectors, such as VS and VS, and

connectors, such as the connector VC, in case she discovers that she has turned her calling device for the wrong number. Theleft hand contactsofthe key RK open the calling bridge, resulting in the release: of. the partly set up connection, and the right hand contacts of the key open the circuit of relay 221- with' the result that thesequenc'eswitch S is, restored to its normal osition in the hcreinbei ore described manner.

lVhat is claimed is: 1. Ina telephone system, a plurality of subscribers lines, a trunk line, an automatic switch for extending a calling one of said lines into engagement with said trunk line, an automatic switch having access to said subscribers lines, means controlled from said trunk line for operating the last named switch to extend a connection to the calling line, a responsive device associated with said trunk line, and means responsiveto the'extension of the last named connection for operating said responsive device overthe first named connection.

:2. In a telcnhone system, a plurality of subscribers lines, a trunk line, an operators switchboard, an automatic" switch for extending a connection from acalling one of said lines to said switchboard via saidt-runk line, a verification switch having access to said subscribers lines, means controlled by said operator over said trunk line for oper ating said verification switch to set up a connection to the calling li'ne,-a responsive device associated with said trunk line, and means responsive to the establishment of the last named connection for operating said responsive device through the first named switch to signal the'operator at said position. I

3. In a telephone system, an operators switchboard,a trunk line, an automatic switch for extending a calling line to said switchboard by way ofsaid trunk line, a second automatic switch, means controlled by the operator at said switchboard for operating said second automatic-switch over said trunk line to set up an auxiliary connection to the said calling line while the first named switch remains operated. a i I 4. In a telephone system, an operators switchboard, aitrunk line divided into two.

inductively coupled sections, an automatic switch for extending a connection from a calling line over the two sections of said trunk line in series to said switchboard, and means controlled by the operator at said switchboard for setting line to said calling line while the connec;

tion from the automatic switch to the first up an auxiliary conncction over the second section of saidtrunk switch and terminating at the other end at said switchboard, an auxiliary switch, a finder switch having access to said trunk line at the automatic end thereof, means for operating the first named switch to extend a connection from a calling line to said switchboard by Way of said trunk line, means controlled by the operator at said switchboard over said trunk line while the first named switch is still operated for operating said finder switch to connect said auxiliary switch to the trunk line, and means also controlled by the operator for setting up an auxiliary connection to the said calling line through the medium of said auxiliary switch. 1

6. In a telephone system, a plurality of subscribers lines, atrunk line, an operators switchboard, means for extending a connection from a calling one of said lines tov said switchboard via said trunk line, a signalling device at said switchboa 7d, means controlled by the operator at said switchboard for extending a temporary connection to the calling line, said temporary connection including a section of said trunk line, and means controlled over said temporary (301k nection and through the first named connection for operating said signalling device to inform the operator that the temporary con nection is established with the calling line.

7. In a telephone system, an operators switchboard, means for extending a connec tion from a calling line to said switchboard, a calling device at said switchboard, automatic switches controlled by said calling device for extending a temporary verifying connection to the calling line, a signalling device at said'switchboard normally inoperative, and a sequence switch also controlled by said'calling device simultaneous with its operation in controlling the setting up of the verifying connection to render said signalling device operative upon the completion of said verifying connection.

8. In a telephone system, a train of automatic switches for extending a calling line to a manual switchboard, a release trunk conductor for maintaining said switches in operated position, means including other automatic switches controlled by the operator in accordance with the number of the calling line for connecting a source of alternating current with said conductor, a signal at said switchboard, and means controlled over said conductor by currcnt'from said source for'controlling said signal.

9. In a telephone system, a train of auto matic switches for extending a calling line to a manual switchboard, a release trunk conductor for maintaining said switches in operated position. means including other switches controlled by the operator for connecting a'source of alternating current with said conductor at a section thereof which is individual to the calling line, and a signal at said switchboard controlled over said conductor by current from said source.

' 10. In an automatic telephone system, a trunk line for extending connections to an operators switchboard, a secondtrunk line for extending connections from said switchboard, the first trunk line only having a terminal at said switchboard, a. finder switch individual to the second trunk line for connecting the same to the first trunk line, and

a circuit for starting said finder controlled by the operator over a section ofsaid first trunk line. i

11. In an automatic telephone system, verifying means for enabling an operator to checl; a calling subscribers number, said means comprising switches and associated apparatus for transmitting adistinctive cur rent over an established connection from a section thereof which is individual to the ailing line, and means for controlling said switches over a portion of the said established connection.

12. In a telephone system, a trunk line, a train of automatic switches for extending a calling line to a manual switchboard via said trunk line, a release trunk conductor for maintaining said switches in operated position, means including other switches controlled by the operator for connecting a source of alternating current with said conductor a signal at said switchboard, and means responsive to said current for controlling said signal over the two talking ,conductors of said trunk line in series.

13. In a telephone system, a plurality of subscribers lines, an operators switchboard,

means for extending aconnection from a calling one of said lines to said switchboard, operator controlled means for extending a temporary connection to the calling line, a signal lamp at said switchboard, and means controlled over said temporary connection and through the first named connection for lighting said lamp signal to inform the op erator that the temporary connection is established with the calling line. r

14:. In a telephone system, a plurality of subscribers lines, an operators switchboard, means for extending a connection from a calling one of said lines to said switchboard, means including an operators headset for answering the call, operator controlled means for extending a temporary connection to the calling line, a signalling device at said switchboard, and means controlled over said temporary connection and said first connection for operating said signalling device to inform the operator that the temporary connection is established with the calling line.

15. In an automatic telephone system, verifying means for enabling an operator to check a calling subscribers number, said form the operator that thetemporary conmeans comprising switches and associated a train of automatic switches for extending a calling line to an operators switchboard via said trunk line, means controlled by the operator at said switchboard for extending a temporary connection to the calling line,

and means responsive to the establishment of said temporary connection for reversing the normal current flow in said trunk line, and a signalling device responsiveto the reversal of current in said trunk line to innection is established with the calling line.

17. In a telephone system, a train of automatic switches for extending acalling line to a manual switchboard, a release trunk conductor for maintaining said switchesin for 'extendin operated position, means includin other switches for connecting a source of a ternating current with said conductor, a signal at said swltchboard common to all the lines in the exchange, and means controlled by current from said source for controlling said signal. v

I 18. In an automatic telephonesystem, a

trunk line for extending connections toan operators switchboard, a second trunk line connections from said switchboard, the rst trunk line only having a terminal at said switchboard, a finder switch individual to the second trunk line for connecting the same to the first trunk line, and a circuit for starting said finder controlled by the operator over a section of said first trunk line while an established connection over'thefirst trunk line to the switchboard is maintained intact.

In witness whereof, I hereunto subscribe my name this 9th day of January, A. D.

JOHN E. OSTLINE. 

